Aims: Pain is a complex sensation that affects the spirit and psychological status and in many cases, using the different drugs for pain relief is required. This study aimed to investigate the effect of alcoholic extract of Brassica rapa root in reducing acute and chronic pain induced by formalin in adult male rats.

Methods: In this experimental study, 40 adult male rats were used that were divided into 5 8membered groups of control, rein, test 1, test 2 and test 3. To cause pain, 0.5ml of 2.5% formalin was injected to the foot of animals subcutaneously . The control group went only under the formalin test. Half an hour before the injection of formalin, the rein group received 1ml of saline and test groups 1, 2 and 3 received doses of 50, 100 and 200mg/kg of alcoholic extract of Brassica rapa roots, respectively. Obtained data was analyzed by using SPSS 18 software and ANOVA and post hoc Tukey tests.

Results: 100 (1.762 ± 0.133) and 200mg/kg (1.550 ± 0.132) of body weight doses of alcoholic extract of Brassica rapa root caused a significant reduction of pain in acute phase in comparison to the control group and 200mg/kg (1.225 ± 0.054) dose of body weight caused a significant reduction of pain in chronic phase in comparison to the control group (1.822 ± 0.114).

Conclusion: Alcoholic extract of Brassica rapa root is useful in pain reducing dose-dependently and time-dependently.